 namespace xlink = "http://www.w3.org/1999/xlink"
 
 [
   xlink:type = "simple"
   xlink:role = "http://www.w3.org/1999/xhtml"
   xlink:arcrole = "http://www.rddl.org/purposes#reference"
   xlink:href = "grammar.xhtml"
 ]
 grammar {
   start = element library { book-element+ }
   author-element =
     element author {
       attribute id { text },
       name-element,
       born-element,
       dead-element?
     }
   book-start =
     attribute id { text },
     isbn-element,
     title-element,
     author-element*
   book-end =
     author-element*,
     character-element*,
     attribute available { text }
   book-element = element book { book-start, book-end }
   born-element = element born { text }
   character-element =
     element character {
       attribute id { text },
       name-element,
       born-element,
       qualification-element
     }
   dead-element = element dead { text }
   isbn-element = element isbn { text }
   name-element = element name { text }
   qualification-element = element qualification { text }
   title-element =
     element title {
       attribute xml:lang { text },
       text
     }
 }
